There has been proposed a work vehicle (refer to, for example, Patent Document 1, which will be described later) including a pair of right and left vehicle frames, a front axle unit, a pair of right and left front wheels, an engine unit, a flywheel unit, and a transmission, wherein the pair of vehicle frames extend in a vehicle longitudinal direction such that plate surfaces thereof are substantially aligned in the vertical direction and face each other, the front axle unit is located below the pair of vehicle frames and is supported by the pair of vehicle frames so as to be provided in the vehicle width direction as well as to have two ends that extend outward in the vehicle width direction from the pair of vehicle frames, the pair of front wheels are supported in a steerable manner by the two ends of the front axle unit, respectively, the engine unit is supported by the pair of vehicle frames, the flywheel unit is connected to a rear end surface of the engine unit, and the transmission is disposed behind and apart from the flywheel unit and operatively receives rotational power from the engine unit by way of the flywheel unit. The pair of vehicle frames include a pair of right and left front frames and a pair of right and left main frames, respectively. The pair of front frames support the front axle unit. The pair of main frames have front ends whose inner surfaces are directly connected to outer surfaces of rear ends of the pair of front frames, and rear ends that are directly connected to side surfaces of a transmission case of the transmission, respectively.
The work vehicle disclosed in Patent Document 1 is useful in view of the feature that the balance of weight can be preferably kept in the longitudinal direction because the front axle unit and the engine unit are disposed in the front section of the vehicle and the transmission is disposed behind and apart from the engine unit in the vehicle longitudinal direction. However, this work vehicle still has possibility for improvement on the following points.
More specifically, it needs to reduce as much as possible a spacing width (a distance in the vehicle width direction) between the pair of front frames, which support the front axle unit having the two ends to which the pair of front wheels are connected, in order to increase the maximum steerable angles of the pair of front wheels without increasing a mounting pitch by which the pair of front wheels are separated from each other in the vehicle width direction (a distance between the pair of front wheels in the vehicle width direction).
However, in the work vehicle disclosed in Patent Document 1, the outer surfaces of the rear ends of the pair of front frames, which support the front axle unit, are connected directly to the inner surfaces of the front ends of the pair of main frames, respectively. Further, the rear ends of the pair of main frames are connected directly to the respective side surfaces of the transmission case of the transmission.
In other words, in the work vehicle disclosed in Patent Document 1, the spacing width between the pair of main frames is defined by the width (the length in the vehicle width direction) of the transmission case. Further, the spacing width between the pair of front frames is defined dependently on the spacing width between the pair of main frames.
Accordingly, it has not been possible to reduce the spacing width between the pair of front frames freely and independently of the spacing width between the pair of main frames. This leads to the problem that the maximum steerable angles of the pair of front wheels cannot be increased.
Moreover, in the work vehicle disclosed in Patent Document 1, the reduction of the spacing width between the pair of front frames is inhibited also for the following reason.
More specifically, the transmission is preferably disposed as low as possible so as to lower the location of a driver's seat disposed above the transmission as well as to lower the center of gravity of the work vehicle.
Further, the engine unit and the flywheel unit are preferably disposed at low positions so as to level as much as possible the vertical positions between the output shaft of the flywheel unit and the input shaft of the transmission.
In order to meet these demands, in the work vehicle disclosed in Patent Document 1, the pair of front frames are spaced apart from each other in the vehicle width direction by a distance allowing at least a lower portion of the flywheel unit, which has a width larger than that of the engine unit, to be interposed between the pair of front frames.
This inhibits the reduction of the spacing width between the pair of front frames, and it is therefore impossible to increase the maximum steerable angles of the front wheels.
Moreover, in the work vehicle in which the engine unit is supported by the pair of vehicle frames with antivibration support mechanisms being interposed therebetween, there needs to be provided a safety mechanism that limits the amount of relative forward shift of the engine unit with respect to the vehicle frames.